Process of manufacturing artificial stone.



\ Patented June 23, 1903.

" WILLIAM OWEN, OF WOKING, ENGLAND.

PROCESS "oF MAN UFACTURING VARTIFIICIAL STONE.

$PEGIFIGATI0R forming part of LettersPatent No. 731,608, dated June 23,1903..

Application filed December 6, 1902.

ing to combine suitable and cheap materials by physical and acceleratedchemical actions into durable and economically-manufactured commercialcommodities, such as bricks,

blocks, slabs, .or the like.

In the manufacture of artificial stone clean sand, tailings, granulatedslag, or any other suitable grit or refractory material may be used incombination with fresh burnt and ground lime or other cementing materialAssuming that sand and lime are the ingredients, the object and themethod of the process may be described as follows:

The objecthas been generally described in the above paragraph-namely, bythe application of physical and chemical actions to combine together thesand and lime into homogeneous articles capable of resisting greatpressure and to withstand the injurious efmanufacturing centers.

fects of'elimate and atmospherical agencies.

shows, first,that. sand considered by atoms is capable of resisting highpressure and is absolutely impervious to the deleterious effects ofclimate or theatmosphere of cities and other densely-populated districtsand It therefore naturally follows that if it can be combined togetherin a compact mass by some combining element which is also possessed ofthe foregoing qualities of resistance a technicallyuseful andcommercially-valuable product is evolved. Second, lime, more especiallysuch as is produced from burnt limestone, will under certaincircumstances rapidly'reassume or reabsorb in a short period of time thecomponent parts which have been expelled from it in the process ofburning.

*The difference between the excessively-hard limestone and the softpowder-like nature of burnt lime is thatqthe application of heat hasexpelled from thelimestonesuch elements as seen No. 134,029. (Nospecimens.)

moisture and the carbonic-acid gases which it contained, thus deprivingit of the agents or powers of adhesion; If, however, means can bedevised to reinstate these agents or powers ofadhesion, partly byreabsorption of the expelled components and partly by creating newelements of combination, a satisfactory result can be attained for thepurpose under consideration. q

. It has been proved that burnt lime when slaked will under normalconditions form new combining substances-namely, carbonates of lime andhydrosilicates of lime-resulting in the hardening of the substances, theprocess of hardening or induration eontinuingindefinitely. It has alsobeen proved that hydrated form therewith the carbonate of lime in thestate in which it was originally constituted.

disputed and that under normal conditions by the slow process of time ahard and durable substance can be produced, the question resolves itselfinto the solution of the proband simultaneously the twin processes ofcreating carbonate of lime and hyvdrosilicate of lime in a short periodof time. In describing the following method or process it should bestated that although the immediate result is an improvement on the workof nature, inasmuch as the product is free from laminations, vents,850., being of uniform texture and density throughout, yet the stonewill continue to harden and ind urate indefinitelyafter manufactureuntil it ultimately becomes harder in the mass than a state of nature byits own action could produce.

be clean, not exceeding three per cent. of loam or other foreign matter.It should be sharp and uniform in size-mot too fine or too coarse. Anacceptable average size of the sand should quartz, or other silieiousmaterial when used instead of sand. The lime should be properly burntand freshly ground to seventy or seventy-five mesh. The sand and 1i meshould then be intimately mixed in proper proportions when in a drystate. The mixing should be thoroughly done, so that each particle oflime will readily'absorb carbonic-acid gas and Granted, therefore, thatthese facts are un- .lem of accelerating by abnormal conditions 7 Thefirst essential part of this method is to I, have suitable ingredients.The sand should be forty to fifty mesh. This applicsalso'to slag,

.of lime with the hydrosilicates.

sand is coated with the finer particles of lime. The proportions forordinary quality of stone may be approximately taken aseighty-five percent. of sand and fifteen per cent. of lime,

by weight; but this proportion necessarily depends upon the hardnesswhich it is desired the stone should have and also upon the quality ofthe limestone from which the lime is' formed-that is, itsrichness incarbonates. For stone of a harder quality a slightly-greater percentageof lime and a slightly less percentage of sand will be used than thatabove stated. The mixture should then be slaked, preferably in a troughinto which moisture at a low pressure can be gently introduced. Moisturesuch as steam or vapor is preferable to water for the slaking of thelime in the mixture, as it will effect the purpose without washing otfthe coatings of lime with which the particles of sand are covered, as isthe case by the violent application or addition of water. It is animportant point to maintain theclose contact of the lime and sandattained in the dry mixing; otherwise the mixture-will have its weakspots, owing to the absence of any combining elements to maintain theaggregation of sand together. Sand cannot of itself have any strength ofadhesion, and it is unsafe to rely upon the adhesion of any uncoatedparticles of sand depending upon the adhesion of the surroundingparticles. When thoroughly slaked and cooled, the mixture is subjectedto high mechanical pressure in a mold to form it intoa compact orhomogeneous mass, which when so formed is relieved of the mechanicalpressure and subjected to a natural or artificial drying action. Whenpartially dried, the molded or formed articles are placed in aninduratingchamber and. subjected to the action of moisture for asufficient period to allow them to become thoroughly saturated, andduring or at the end of this period carbonic-acid gas is admitted to theindurating-chamher direct from the lime-burning retorts or otherconvenient source, the inflowing gas being mixed with moisture eitherbefore, after, or during its entry into the chamber with the saturatingmoisture to enable the indurated articles to readily absorb thecarbonic-acid gas simultaneously with the absorption of the moisture andcause the simultaneous formation of the carbonate When suificient timehas elapsed to complete the indu: ration of the molded or formedarticles in the indurating-chamber, the flow of the carbonicacid gas andthe moisture is gradually reduced and finally stopped. During the flowof the moisture and carbonic-acid gas the chemical reaction taking placein the molded articles is the reconstitution of the lime carbonates bythe contact and absorption of the carbonicacid gas and the formation ofthe hydrosilicate of lime by the combination of hydrated carbonates andthe soluble silica present in thepressed mixture. Under such abnormalconditions thus created these hardenin g elements are very rapidlyformed, and it is found by experience that the molded articles will in avery short time be sufficiently ind urated to be removed from theinduratingchamber'and may, if desired, be immediately used in masonry.

Longer periods of exposure to the treatment in the indurating-chamberwill result in a corresponding increase in the hardness of the articlesuntil the ultimate power of absorption and induration is attained.

On removal from the indurating-chamber if immediately tested thecrushing strains of the articles will be found. equal to those of averyhigh class building-stone, while experimental tests prove that the"exposure will continue to harden the articles indefinitely- I desire itto be understood that the same process is also applicable to theinduration of artificial stone made of granulated slag,

tailings, or other refractory material com- 1 binedwith lime.

Having thus fully described my invention,

what I claim as new, and desire to secure by Letters Patent, is-

The herein-described process for manufac turing artificial stone,comprising the mixing of from forty to fifty mesh sand with seventy toseventy-five meshlime in the dry state so that each grain of sand iscoated with finer particles of lime, the said sand and lime being mixedin the proportions of eighty-five.

per cent., sand and fifteen per cent. lime, then subjecting the productto enough vapor to properly slake the lime at a low pressure

